1. Field of the Invention
The present invention relates to a power line communication apparatus and a power line communication method for data transmission via connection to a power line.
2. Description of Related Art
Recently proposed is a power line communication system that superimposes high-frequency signals on power lines that transfer power, including a commercial power supply, in order to transmit data. A communication apparatus employing a multi-carrier transmission system, which transmits and receives multi-carrier communication signals, is known as such power line communication system (e.g., Japanese Patent Laid-open Publication 2000-165304).
In such power line communication system, the availability of power line outlets, which are located in each room of a building, makes it convenient to connect terminal apparatuses. However, wiring of power lines, which are used as transmission lines, is very complicated. Further, noises and impedance fluctuations occur due to a variety of electric appliances connected. Thus, fluctuations in transmission characteristics are supposedly large among wired communications.
Thus, when transmitting data between the terminal apparatuses using all frequency bands available for the power lines, a desired transmission rate may not be achieved, thereby adversely affecting high-speed data transmission. With the above-described conventional power line communication apparatus, however, a user of the communication apparatus can not easily confirm a transmission status when the transmission characteristics of the power line are affected by noises or impedance fluctuation.